title: Structural diversity of class 1 integrons and their associated gene cassettes in Klebsiella pneumoniae isolates from a hospital in China.
abstract: BACKGROUND
  Klebsiella pneumoniae strains carrying class 1 integrons are becoming more common worldwide, and their role in the dissemination of drug resistance is significant. The aim of this study was to characterize the structural diversity of class 1 integrons and their associated gene cassettes in K. pneumoniae isolates from hospital settings.
  
  
  RESULTS
  We analyzed a total of 176 K. pneumoniae isolates in a tertiary-care hospital in Beijing, China for the period of November 1, 2010-October 31, 2011. The presence of class 1 integrons and gene cassettes was analyzed by PCR and sequencing. The prevalence of class 1 integrons was 51.1% (90/176). Fourteen different gene cassettes and 10 different gene cassette arrays were detected. dfrA and aadA cassettes were predominant and cassette combination dfrA1-orfC was most frequently found (13.6%, 24/176). Strong association between resistance to a variety of drugs (both phenotypes and the associated genes) and the presence of class 1 integrons was observed. In addition, we also identified an association between some previously identified prevalent sequence types (such as ST11, ST15, ST147, ST562, and ST716) and the presence of class 1 integrons.
  
  
  CONCLUSIONS
  Data from this study demonstrated that class 1 integrons are highly diverse and are associated with a variety of drug resistance phenotypes, drug resistance genes, as well as genotypes among K. pneumoniae isolates. Continuous monitoring of gene cassettes in class 1 integrons is warranted to improve the understanding and control of drug resistance among hospital settings.
authors.affiliation: CAS Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing, China.
authors.forename: Bin
authors.initials: B
authors.lastname: Li
authors.forename: Yongfei
authors.initials: Y
authors.lastname: Hu
authors.forename: Qi
authors.initials: Q
authors.lastname: Wang
authors.forename: Yong
authors.initials: Y
authors.lastname: Yi
authors.forename: Patrick C Y
authors.initials: PC
authors.lastname: Woo
authors.forename: Hua
authors.initials: H
authors.lastname: Jing
authors.forename: Baoli
authors.initials: B
authors.lastname: Zhu
authors.forename: Cui Hua
authors.initials: CH
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D002681:China / Q000453:epidemiology; D019295:Computational Biology; D003428:Cross Infection / Q000453:epidemiology* / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D024881:Drug Resistance, Bacterial / Q000235:genetics*; D006801:Humans; D032023:Integrons / Q000235:genetics*; D007710:Klebsiella Infections / Q000453:epidemiology* / Q000235:genetics*; D007711:Klebsiella pneumoniae / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA
chemical_list: D017931:DNA Primers